MEDICINE

Want to know odds of a lucid old age?

Let's say your father has Alzheimer's disease. The withering of his memory is agonizing, and the toll on you grows worse the more he declines.

Your doctor points out that a particular variant of a gene called apolipoprotein E is associated with the likelihood of developing the debilitating disease. A test is available to see if you have it.

Should you have the test?

Until now, the advice of the medical community has been to decline. Testing positive for a single copy of the variant -- known as APOE e4 -- means one's risk is higher, and having two copies is even higher. But it's no guarantee of dementia in your future. Nor is an alternate version of APOE an assurance of lucid old age. The potential downside of wigging out over a bad test result outweighs any possible benefits, doctors have counseled, especially because there's no effective treatment for Alzheimer's.

Testing reactions

Dr. Robert Green, a neurologist and co-director of the Alzheimer's Disease Clinical & Research Program at Boston University, decided to test that assumption.

Together with colleagues, he recruited 162 adult children of Alzheimer's patients for a randomized clinical trial. The study volunteers attended a 90-minute session with a genetic counselor about the pros and cons of APOE testing. Then they had individual meetings and blood draws.

When they returned for their follow-up appointments, 111 of the volunteers received their test results. The other 51 weren't told their APOE status -- they were only shown charts depicting the incidence of Alzheimer's disease in the general population and among those who are first-degree relatives of an Alzheimer's patient.

The researchers predicted that with appropriate genetic counseling, the people who received their test results wouldn't freak out any more than those who didn't. They were right, according to the data published Thursday in the New England Journal of Medicine.

Based on standard measures of anxiety and depression, there were no significant differences between the two groups either six weeks, six months or a year after the test results were (or were not) revealed.

So does this mean doctors should start offering the tests? Not so fast, the researchers cautioned.

The people who got bad test results might become more anxious or depressed in years to come -- say, after blanking out on a friend's name or having their first "senior moment." What's more, the study volunteers were pre-screened for good mental health; a more troubled person might not cope with the results as well. Failing to see a genetic counselor could also be a problem.

Possible problems

In a related editorial, two researchers from the University of Minnesota School of Public Health and Center on Aging pointed out that the volunteers were different from regular people in another way as well -- they apparently were willing to go through counseling and have their blood drawn but not get their test results at the end. Maybe they were inherently less interested in their APOE status than the patients who request the test from doctors. (Fifteen percent of primary-care physicians who treat Alzheimer's patients say they've already been asked about a test for APOE.)

Moreover, the pair wrote, the study failed to take into account the social and financial implications of knowing one's APOE status. What if a fatalistic APOE e4 carrier decided to blow his life's savings before his expected Alzheimer's set in? What if insurance companies declined to write him a policy for disability or life insurance? (Only employment and health insurance decisions are covered by the Genetic Information Nondiscrimination Act.)

"Perhaps the social effects of genetic testing will be less worrisome by the time a clinical rationale for the test becomes apparent," they concluded.